Substituted succinamic acid deicer



Un edwe Pa e? 2,982,631 SUBSTITUTED SUCCINAMIC ACID DEICER Harry J. Andress, Jr., Pitman, N.J., assignor to Socony Mobil Oil Company, Inc., a corporation of New York No Drawing. Filed Dec. 29, 1958, Ser. No. 783,083

3 Claims.- (CI. 44-71) This invention relates to gasoline-compositions adapted to improve the operation of internal combustion engines. It is more particularly concerned with motor fuels'that provide improved engine operation under cool, humid weather conditions. "As is well known to those skilled in the art, frequent stalling of automobile engines, especially during the warmup period, has been a common occurrence. This difiiculty is most pronounced in postwar cars having automatic transmissions and a consequent limit on the maximum permissible idle speed, although it also occurs in cars without automatic transmissions. Stalling of this type, of course, is a definite safety hazard, as well as a decided inconvenience in frequent restarting of the engine.

It is now recognized that stalling during the warmup period is attributable to the formation of iceon the throt tle plate and the carburetor barrel near it. The water will give ditficulty in damp, cool weather.

though this may be the case for givenseries of gase 5v lines, however, it is not the sole and controlling factor.'. Gasolines of-higher mid-boiling point but a low initial} boiling point (e.g., full boiling range gasolines) can in;

duce stalling when the aforementioned stallinducing at-',

mospheric conditions are prevalent.- Thus, any gasoline engine operation, however, control of stalling by means of volatility is not feasible, because other performance characteristics are effected.

It has now been found that stalling during engine warmup can be overcome simply and economically. It has a motor fuel adapted to prevent stalling during engine warmup in cool, humid weather. A specific object is to provide an antistall gasoline containing certain succinamic acids. Other objects and advantages of this invention will become apparent .to those skilled in the art, from which forms the ice does not come from the gasoline, 4

60 F. and the relative humidity is about 65 percent and higher, up to 100 percent. The most critical conditions are temperatures of 40 F. and 100 percent relative humidity.

As the gasoline evaporates in the carburetor, it reduces the temperature of the surrounding metal by as much as F. Moisture in the incoming air comes in contact with these parts and begins to build up ice on the throttle plate and in the carburetor barrel. The more moist this air is, the greater the buildup of ice. Then, when the engine is idled, the throttle plate closes and the ice chokes off the normal small flow of air through the small clearance between the throttle plate and the carburetor wall. This causes the engine to stall. The engine can usually be restarted when the heat from the exhaust manifold melts the ice sufliciently. However, stalling will continue until the engine is completely warmed Icing may also occur in the carburetors of some vehicles when cruising at speeds of 30-60 m.p.h. Such icing is a particular problem in the case of certain trucks and cars equipped with carburetors having Venturi-type fuelair mixing tubes (emulsion tubes). Such carburetors are found in trucks and in many European cars. The ice builds up in the tube and restricts the flow of air, thereby enriching the fuel mixture and reducing efficiency. Eventually the engine may stall.

Gasoline is a mixture of hydrocarbons having an initial boiling point falling between about 75 F; and about 135 F. and an end-boiling point falling between about 250 F. and about 450 F. The boiling range of the gasoline, of course, reflects on its volatility. Thus, a

" higher boiling gasoline will be less volatile and give less stalling difliculty. It has been proposed in the art that a gasoline having an A.S.T.M. mid-boiling (50%) point of 310 'F. or higher will not be subject to stalling. Al-

the following detailed description. In general, this inventionprovides a motorgasoline containing a small amount, sufiicient to inhibit stalling, or an amic acid of alkenyl succinic acid anhydride and tris (hydroxymethyl) amino methane. The novel addition agents of this invention are. the amic acids obtained by' condensing equimolar amounts of an alkenyl succinic acid anhydride and IIlS-(hYdlOXYf methyl) amino methane, without formation of water of condensation. The condensation takes place readily upon heating the acid anhydride reactant and the amino compound reactant at temperatures ranging from ambient temperatures and upwards. The reaction is an amide formation reaction effected by the well-known addition I of the anhydride group to an amino group. This addi reaction temperature selected. Ordinarily addition of the acid anhydride is substantially complete within a few min utes. In order to ensure complete reaction, however, it is preferred to continueheating for severalhours, even as much as 10 hours. lngeneral, the reaction time varies between several minutes and about ten hours. If de} sired, non-polar solvents, such as benzene,-toluene, kerosines, and xylene, can be used to improve fluidity.

The alkenyl succinic acid anhydride reactant can have between 8 and 16 carbon atoms in the alkenyl radical,

dridc, tetrapropenyl succin.c acid anhydride, tetradecenyl I succinic acid anhydride, and hexadecenyl succinic acid anhydride.

Although the anhydride is preferred, the compounds l of this invention can be prepared from the correspond;

ing alkenyl succinic acid. In this case, the condensation with tris-(hydroxymethyl) amino methane is accom panied by formation of one mole of water per mole'of amine. The reaction, in this case, is carried out at temperatures of between about Cjand about 0., although the reaction can be effected at temperatures I above and below this range. The reaction will proceed until one mole of water is evolved per mole of'alkenyl ,succinic acid reactant, usually six to ten hours. In order lfatented May 2,1961 Q In modern to facilitate the removal of water, to effect a more complete reaction in accordance with the principle of Le Chatelier, a hydrocarbon solvent which forms an azeo tropic mixture with water can be added to the reaction mixture. Heating is continued until rernoval of water by azeotropic distillation has substantially ceased. 'Examples of wellknown solvents that form azeotropes are benzene, toluene, and xylene.

The compounds of this invention can exist in either or both of the following structural forms:

wherein R is an alkenyl radical of 8 to 16 carbon atoms, preferably 10 to 14 carbon atoms.

The amount of substituted succinamic acid that is added to the motor gasoline will vary between about 0.005 percent and about 0.5 percent, by weight, of the gasoline. In preferred practice, amounts varying between about 0.01 percent and about 0.05 percent, by weight, are used.

The antistall additives of the invention may be used in the gasoline along with other antistall addition agents or other additives designed to impart other improved properties thereto. Thus, anti-knock agents, pre-ignition inhibitors, anti-rust agents, metal-deactivators, dyes, antioxidants, detergents, etc., may be present in the gasoline. Also, the gasoline may contain afsmall amount, ;from about 0.01 percent to about 1 percent, by weight, of a solvent oil or upperlube. Suitable oils, for example, include Coastal and Mid-Continent distillate oils'having viscosities within therange 'of from about 50 to about 500 S.U.S. at 100 F. "Synthetic oils, such as diester oils, polyalkylcne glycols, silicones, phosphate esters, polypropylenes, polybutylenes and the like, may alsobe used.

The following examples are for the purpose of illustrating this invention and demonstrating the effectiveness thereof. This invention is not to be limited to the specific composition set forth in the examples or to the operations and manipulations involved. Other materials and formulations as described hereinbefore can be used, as those skilled in the art will readily understand.

The ability of an additive to inhibit icing is demonstrated in the following test:

HILLMAN-MINX ENGINE TEST A downdraft Solex FAI-30 carburetor was mounted on a standard 1953 Hillman-Minx engine. The engine was connected to a 7.5 horsepower induction motor and operated under load at.2800 r.p.m. This was equivalent to driving at about 40 miles .per hour.

The Solex carburetor was especially prone to icing on its spraying well which is located in the center of the carburetor throat. The spraying well is a cylindrical metal tube with apertures through which a fuel-air mixture is sprayed into the carburetor throat. Evaporation of the fuel refrigerates the spraying well.

As ice formed on the well;itxrestricted the' flow of.air through the carburetor and caused a drop in pressure. This pressure changewas recorded .by. a manometer connected above and below the point of ice deposition.

Temperatures at this point were measured by a thermocouple attached to the well. The entire carburetor was enclosed in an asbestos chamber that was connected to an ice tower. Air at 34-37 F. and -100 percent relative humidity was passed through the carburetor at constant velocity.

In conducting a test the engine was first run until the spraying well reached an equilibrium temperature of about 20-25 F. The fuel flow was then stopped and the engine was driven' by the induction motor until the spraying well reached 45 F. (warm ambient air was admitted to the carburetor during this period). Fuel flow was now restored to the engine and the run was started. As the engine operated under load, ice deposited on the spraying well. The pressure drop across the ice formation was recorded at one minute intervals for 20 minutes. Several tests were made on each fuel blend and the results were averaged.

A fuel rating was obtained by using these pressure readings to calculate the percentage of the carburetor throat area that would be blocked with ice after 20 minutes. The percent of annular area in the carburetor that is blocked by ice determines the amount of pressure drop across the annular opening in any given installation. Thus, for each carburetor, the amount of throat area blocked by ice is related to the amount of pressure drop above and below the point of ice deposition. The relationship between pressure drop and area blocked was determined to calibrate the carburetor, as follows:

A series of flanged cylinders were prepared, which fitted over the emulsion tube and blocked a portion of the annular opening. Each tube had a different, but known size flange. Thus, it was known what fraction of the annular area was blocked by each flange. The engine was operated with a flanged cylinder in the carburetor and the amount of pressure drop was noted and recorded. This operation was repeated with each flange.

From the data, thus obtained, the relationship between pressure drop and amount of throat area blocked was plotted. Then, when runs were made using blank fuel or inhibited (test) fuel, but with no flanged inserts in the carburetor, the throat area blocked by ice was determined from the amount of pressure drop. The average area blocked during the 20-minute run is obtained from the summation of the one-minute observations.

It will be appreciated, of course, that calibration curves will vary with each carburetor, but any carburetor can be readily calibrated as aforedescribed. As is the case in many test procedures, results can vary from time to time, because of slight variations in test conditions, vapor pressure of fuel, and even techniques of individual operators. Thus, each day a test run is made, a blank fuel should be run. This provides a reference point, so that even if values determined may not be finite, comparison of a test fuel result with the result on the blank fuel gives a positive order of magnitude, i.e., one can say for example that an additive cut the amount of ice formation by some certain percentage.

The base gasoline used to evaluate the antistall additives was a blend, by volume, of 66 percent catalytically cracked gasoline, 2 percent natural gasoline, 12 percent benzene, 8 percent toluene, and 12 percent butane. It had an A.S.T.M. boiling range of 80 F. to 394 F., with a mid-boiling point of 200 F.

Example Equimolar amounts of tetrapropenyl succinic acid anhydride and tris-(hydroxymethyl) amino methane, in xylene diluent, were stirred at C. for 4 hours. The tetrapropenyl group of the acid anhydride was obtained from tetrapropylene, i.e., propylene tetramer. The product was a clear, reddish colored solution, that was viscous at room temperature (20 C.). It was a xylene solution of ld I-t ris(hydroxymethyl) methyltetrapropenyl succinamic 8C1 5 The additive of the example was also blended in the test gasoline and tested on the Hillman-Minx engine test. Pertinent data and results are set forth in Table I.

TABLE I Percent An- Additive Ooncn, Wt. Percent nular Area Blocked With Ice It will be apparent from the data in Table I that substituted succinamic acids of this invention are effective antistall agents. Not all are equivalent in performance, but all will be effective.

Although the present invention has been described with preferred embodiments, it is to be understood that modifications and variations may be resorted to, without departing from the spirit and scope of this invention, as those skilled in the art will readily understand. Such variations and modifications are considered to be within the purview and scope of the appended claims.

References Cited in the file of this patent UNITED STATES PATENTS 2,588,412 Rocchini Mar. 11,1952 2,706,677 Duncan et a1. Apr. 19, 1955 2,843,464 Gaston et al. July 15, 1958 2,862,800 Cantrell et a1. Dec. 2, 1958 2,886,423 Vitalis et a1. May 12, 1959 2,906,613 Mills Sept. 29, 1959 OTHER REFERENCES Petroleum Refining With' Chemicals, Kalichevsky and Kobe, Elsevier Pub. Co., 1956, page 480. 

1. A MOTOR GASOLINE CONTAINING A SMALL AMOUNT, SUFFICIENT TO INHIBIT ICING, OF AN N-TRIS(HYDROXYMETHYL) METHYLALKENYLSUCCINAMIC ACID, HAVING BETWEEN 8 AND 16 CARBON ATOMS PER ALKENYL RADICAL. 